Given all the excitement, let’s first take a look at the transcript of what the President actually said on this topic:

We will respond to the threat of climate change, knowing that the failure to do so would betray our children and future generations. Some may still deny the overwhelming judgment of science, but none can avoid the devastating impact of raging fires, and crippling drought, and more powerful storms. The path towards sustainable energy sources will be long and sometimes difficult. But American cannot resist this transition. We must lead it. We cannot cede to other nations the technology that will power new jobs and new industries. We must claim its promise. That’s how we will maintain our economic vitality and our national treasure, our forests and waterways, our crop lands and snow capped peaks. That is how we will preserve our planet, commanded to our care by God.

Q: What are the top priorities for a second Obama administration in energy and environmental policy?

A: The Obama administration faces a number of impending challenges in the energy and environmental policy realm in its second term, which I would characterize – in very general terms – as finding balance among three competing factors: (1) demands from some constituencies for more aggressive environmental policies; (2) demands from other constituencies – principally in the Congress – for progress on so-called “energy security;” and (3) recognition that nothing meaningful is likely to happen if the country’s economic problems are not addressed.

Q: What will be the potential challenges/roadblocks in the way of implementing those top priorities?

The numbers are dramatic. For example, when the Clean Air Act Amendments of 1990 that established the landmark SO2 allowance trading system were being considered in the U.S. Congress, political support was not divided on partisan lines. Indeed, environmental and energy debates from the 1970s through much of the 1990s typically broke along geographic lines, rather than partisan lines, with key parameters being degree of urbanization and reliance on specific fuel types, such as coal versus natural gas. The Clean Air Act Amendments of 1990 passed the U.S. Senate by a vote of 89-11 with 87 percent of Republican members and 91 percent of Democrats voting yea, and the legislation passed the House of Representatives by a vote of 401-21 with 87 percent of Republicans and 96 percent of Democrats voting in support.

But, 20 years later when climate change legislation was receiving serious consideration in Washington, environmental politics had changed dramatically, with Congressional support for environmental legislation coming mainly to reflect partisan divisions. In 2009, the U.S. House of Representatives passed the American Clean Energy and Security Act of 2009 (H.R. 2454), often known as the Waxman-Markey bill, that included an economy-wide cap-and-trade system to cut carbon dioxide (CO2) emissions. The Waxman-Markey bill passed by a narrow margin of 219-212, with support from 83 percent of Democrats, but only 4 percent of Republicans. (In July 2010, the U.S. Senate abandoned its attempt to pass companion legislation.) Political polarization in the Congress (and the country) has implications far beyond energy and environmental policy, but it is particularly striking in this realm.

Q: In the Obama administration’s second term, are there openings/possibilities for compromises in those areas?

A: It is conceivable – but in my view, unlikely – that there may be an opening for implicit (not explicit) “climate policy” through a carbon tax. At a minimum, we should ask whether the defeat of cap-and-trade in the U.S. Congress, the virtual unwillingness over the past 18 months of the Obama White House to utter the phrase “cap-and-trade” in public, and the defeat of Republican Presidential candidate Mitt Romney indicate that there is a new opening for serious consideration of a carbon-tax approach to meaningful CO2 emissions reductions in the United States.

Clearly, this “opening” is being embraced with enthusiasm in the policy wonk world. But what about in the real political world? The good news is that a carbon tax is not “cap-and-trade.” That presumably helps with the political messaging! But if conservatives were able to tarnish cap-and-trade as “cap-and-tax,” it surely will be considerably easier to label a tax – as a tax! Also, note that President Obama’s silence extends beyond disdain for cap-and-trade per se. Rather, it covers all carbon-pricing regimes.

So as a possible new front in the climate policy wars, I remain very skeptical that an explicit carbon tax proposal will gain favor in Washington. Note that the only election outcome that could have lead to an aggressive and successful move to a meaningful nationwide carbon pricing regime would have been: the Democrats took back control of the House of Representatives, the Democrats achieved a 60+ vote margin in the Senate, and the President was reelected. Only the last of these happened. It’s not enough.

A more promising possibility – though still unlikely – is that if Republicans and Democrats join to cooperate with the Obama White House to work constructively to address the short-term and long-term budgetary deficits the U.S. government faces, and if as part of this they decide to include not only cuts in government expenditures, but also some significant “revenue enhancements” (the t-word is not allowed), and if (I know, this is getting to be a lot of “ifs”) it turns out to be easier politically to eschew increases in taxes on labor and investment and turn to taxes on consumption, then there could be a political opening for new energy taxes, even a carbon tax.

Such a carbon tax – if intended to help alleviate budget deficits – could not be the economist’s favorite, a revenue-neutral tax swap of cutting distortionary taxes in exchange for implementing a carbon tax. Rather, as a revenue-raising mechanism – like the Obama administration’s February 2009 budget for a 100%-auction of allowances in a cap-and-trade scheme – it would be a new tax, pure and simple. Those who recall the 1993 failure of the Clinton administration’s BTU-tax proposal – with a less polarized and more cooperative Congress than today’s – will not be optimistic.

Nor is it clear that a carbon tax would enjoy more support in budget talks than a value added tax (VAT) or a Federal sales tax. The key question is whether the phrases “climate policy” and “carbon tax” are likely to expand or narrow the coalition of support for an already tough budgetary reconciliation measure. The key group to bring on board will presumably be conservative Republicans, and it is difficult to picture them being more willing to break their Grover Norquist pledges because it’s for a carbon tax.

Combined with that is Assembly Bill 32 (AB 32) in the state of California, which includes a CO2 cap-and-trade system that is more ambitious in percentage terms than Waxman-Markey was in the U.S. Congress, and which became binding on January 1, 2013. Add to that the recent economic recession, which reduced emissions. And more important than any of those are the effects of developing new, unconventional sources of natural gas in the United States on the supply, price, and price trajectory of natural gas, and the consequent dramatic movement that has occurred from coal to natural gas for generating electricity. In other words, there will be actions having significant implications for climate, but most will not be called “climate policy,” and all will be within the regulatory and executive order domain, not new legislation.

Q: Are there lessons that a second Obama administration can draw upon from the first administration, or from history, when constructing its energy & environmental policy over the next four years?

A: It will take a great deal of dedicated effort and profound luck to find political openings that can bridge the wide partisan divide that exists on climate change policy and other environmental issues. Think about the following. Nearly all our major environmental laws were passed in the wake of highly publicized environmental events or “disasters,” including the spontaneous combustion of the Cuyahoga River in Cleveland, Ohio, in 1969, and the discovery of toxic substances at Love Canal in Niagara Falls, New York, in the mid-1970s. But note that the day after the Cuyahoga River caught on fire, no article in The Cleveland Plain Dealer commented that the cause was uncertain, that rivers periodically catch on fire from natural causes. On the contrary, it was immediately apparent that the cause was waste dumped into the river by adjacent industries. A direct consequence of the observed “disaster” was, of course, the Clean Water Act of 1972.

But climate change is distinctly different. Unlike the environmental threats addressed successfully in past U.S. legislation, climate change is essentially unobservable to the general population. We observe the weather, not the climate. Notwithstanding last year’s experience with Super Storm Sandy, it remains true that until there is an obvious, sudden, and perhaps cataclysmic event – such as a loss of part of the Antarctic ice sheet leading to a dramatic sea-level rise – it is unlikely that public opinion in the United States will provide the tremendous bottom-up demand that inspired previous congressional action on the environment over the past forty years.

That need not mean that there can be no truly meaningful, economy-wide climate policy (such as carbon-pricing) until disaster has struck. But it does mean that bottom-up popular demand may not come in time, and that instead what will be required is inspired leadership at the highest level that can somehow bridge the debilitating partisan political divide.

Robert Stavins is the Albert Pratt Professor of Business and Government, Director, Harvard Environmental Economics Program and Chairman, Environment & Natural Resources Faculty Group at the John F. Kennedy School of Government, Harvard University